1. Field of the Invention
This invention relates to new methods or processes for bonding seams in protective garments made of man-made fabrics such as a non-woven spunbonded olefin having one laminated side and one unlaminated side, in which such bonding is efficiently and effectively accomplished without undesirable hole-creating stitching.
2. Description of the Prior Act
In various industries, it is necessary for certain employees and others to be in close proximity to hazardous chemicals and other hazardous matter. Local, state, and federal laws and/or regulations often require the use of protective garments under such circumstances. It is frequently not feasible to utilize "permanent" protective garments because of the necessity to decontaminate the garments regularly, which may be impossible or prohibitively expensive. A widely used alternative to such permanent protective garments is the disposable garment, made of man-made materials which are lightweight, resistant to tearing and abrasion, and relatively impermeable to hazardous substances. Such synthetic fabrics are available, such as spunbounded olefin, which are very satisfactory. They are good barriers to particulates and a broad range of chemicals, have high tensile strength and tear resistance, are light weight and dyeable, and are reasonably economical. An example of this synthetic fabric is sold by E. I. du Pont de Nemours & Co. under its trademark Tyvek, to which may be added a polyethylene or polyvinylidine chloride film coat or lamination on one of its two sides to make it even more impervious to hazardous substances.
A technical problem in using such synthetic fabrics is how to form garments therefrom without significant loss of the favorable properties of the fabrics. In virtually all instances, a stitching process is used in whole or in substantial part to form garments from such synthetic materials so that they will conform generally to the shape of the human body. However, the stitching process obviously results in the creation of many holes in the fabric which are points of vulnerability through which hazardous gases, liquids and some small solid particulates can penetrate, with possible damage to the body or inner clothing, or both, of the person wearing the protective garment. It is thus desirable to minimize to the extent possible the use of traditional stitching methods which create such vulnerable holes.
One patent, Goldstein U.S. Pat. No. 4,272,851, attempts to solve this problem by ultrasonically bonding together edges of synthetic fabric, preferably polyethylene coated (laminated) Tyvek. However, Goldstein suggests the ultrasonic bonding of congruent edges of the Tyvek, presumably laminated side to laminated side. This procedure results in a seam which has inadequate resistance to rupture from shearing. In order to give greater strength against shear stresses, Goldstein adds a binding along the folded back seam, which binding is sewed on by traditional stitching means. While the multiple layers so stitched may be somewhat more protective than earlier stitching methods, it is still possible for hazardous chemicals and substances to get inside the garment through the holes created by sewing.
There has not existed prior to the present invention any means of totally eliminating stitching along the seams of protective garments made with spunbonded olefin or polyolefin fabrics so as to eliminate holes created by the stitching.